Idling turbo-charged engines: a necessary evil?

Dear Car Talk

Dear Car Talk | Sep 01, 1993

Dear Tom and Ray:

I recently read an advertisement for a product called a Turbo Timer that leaves the engine running at idle for up to ten minutes after you park the car and remove the keys. The ad claimed that this would stabilize exhaust temperatures and prevent oil coking. I just bought a new Eagle Talon Tsi with a turbo, and I want to take the best possible care of it. Do you think this would be a worthwhile investment?

RAY: I don't think so, Steve. I'm not convinced that leaving your car running unattended for ten minutes is a great idea. I mean, I'd think it was a great idea if I were a teen ager looking to take a turbocharged car out for a joy ride, but I'm not sure it's a great idea if you're the owner.

TOM: The reason they're selling this device is because on turbocharged engines, you're supposed to let the engine idle for 30 seconds to a minute after you stop driving. That lets the turbo cool down, and lets the oil drain out of it, which prevents oil coking (a crusting of the oil that can eventually ruin the turbo).

RAY: But if I were you, I'd take a two-pronged investment approach. First, I'd invest in the longest extended warranty you can buy. Because turbos work by "forcing" more performance out of the engine, they're hard on the every piece of the drive train. So I'd look to protect the whole car, not just the turbo.

TOM: Second, I'd invest in the Book of the Month club. The reason most people don't let their turbocharged cars idle for a minute is because they get bored just sitting there. So I'd get the club's monthly selection, and sit there and read two or three pages every time you park the car. You'll be all set, Steven.

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